One million Telewest customers have been blacklisted for sending spam by one of the most powerful anti-spam organisations on the Web.
The Spam Prevention Early Warning System (SPEWS), whose blacklist is referenced by many anti-spam controls, imposed the block in response to the high number of Telewest customers whose machines have become compromised and taken over for the purpose of sending spam.
Matt Peachey, managing director of IronPort, the security firm whose Senderbase system first revealed the extent of Telewest's spam problem, told ZDNet UK sister site silicon.com: "The ISPs know they're spamming but they're reluctant to put things in place which block mail. With ISPs it's not about what comes into their networks, it's about what goes out."
Despite such apparent warnings a spokesman for Telewest said the company believes SPEWS' actions have been "a little heavy-handed".
And Peachey is inclined to agree. "I'm not surprised this has happened but I am surprised at the number of IP addresses which have been blacklisted," he said
Peachey says there are around 17,000 IP addresses on the blueyonder.co.uk domain which are pumping out spam — yet the SPEWS blacklisting applies to more than 900,000.
"This is why blacklists are so problematic," said Peachey. "There will be a lot of people who are blacklisted who have been doing absolutely nothing wrong."
However, Telewest is holding back from any further criticism of SPEWS.
"We have to let them get on with what they do and concentrate on our own game," the spokesman added. He accepted Telewest must take some responsibility for the situation reaching such a crisis point but said: "It's an industry issue which every ISP suffers."
The Telewest spokesman said: "We're doing our best to contact customers and we are talking them through physically cleaning up their PCs."
"Later this year we are launching a very comprehensive security package for our customers including a free firewall, free anti-spam and free antivirus," he added.
Currently Blueyonder.co.uk is the ninth in the Senderbase list of email generating domains — only two places behind Hotmail and two ahead of AOL.com.
According to Senderbase, blueyonder.co.uk addresses are generating 90.4 million emails per day. The company confirmed it has around 700,000 customers, with up-to-date figures due for release this Thursday.